Handle *long* lines tail visualization.

[gnu-emacs] / lisp / blank-mode.el

;;; blank-mode.el --- minor mode to visualize TAB, (HARD) SPACE, NEWLINE

;; Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
;;   Free Software Foundation, Inc.

;; Author: Vinicius Jose Latorre <viniciusjl@ig.com.br>
;; Maintainer: Vinicius Jose Latorre <viniciusjl@ig.com.br>
;; Keywords: data, wp
;; Version: 9.1
;; X-URL: http://www.emacswiki.org/cgi-bin/wiki/ViniciusJoseLatorre

;; This file is part of GNU Emacs.

;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published
;; by the Free Software Foundation; either version 3, or (at your
;; option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful, but
;; WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
;; General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:

;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; Introduction
;; ------------
;;
;; This package is a minor mode to visualize blanks (TAB, (HARD) SPACE
;; and NEWLINE).
;;
;; blank-mode uses two ways to visualize blanks: faces and display
;; table.
;;
;; * Faces are used to highlight the background with a color.
;;   blank-mode uses font-lock to highlight blank characters.
;;
;; * Display table changes the way a character is displayed, that is,
;;   it provides a visual mark for characters, for example, at the end
;;   of line (?\xB6), at SPACEs (?\xB7) and at TABs (?\xBB).
;;
;; The `blank-style' and `blank-chars' variables are used to select
;; which way should be used to visualize blanks.
;;
;; Note that when blank-mode is turned on, blank-mode saves the
;; font-lock state, that is, if font-lock is on or off.  And
;; blank-mode restores the font-lock state when it is turned off.  So,
;; if blank-mode is turned on and font-lock is off, blank-mode also
;; turns on the font-lock to highlight blanks, but the font-lock will
;; be turned off when blank-mode is turned off.  Thus, turn on
;; font-lock before blank-mode is on, if you want that font-lock
;; continues on after blank-mode is turned off.
;;
;; When blank-mode is on, it takes care of highlighting some special
;; characters over the default mechanism of `nobreak-char-display'
;; (which see) and `show-trailing-whitespace' (which see).
;;
;; There are two ways of using blank-mode: local and global.
;;
;; * Local blank-mode affects only the current buffer.
;;
;; * Global blank-mode affects all current and future buffers.  That
;;   is, if you turn on global blank-mode and then create a new
;;   buffer, the new buffer will also have blank-mode on.  The
;;   `blank-global-modes' variable controls which major-mode will be
;;   automagically turned on.
;;
;; You can mix the local and global usage without any conflict.  But
;; local blank-mode has priority over global blank-mode.  Blank mode
;; is active in a buffer if you have enabled it in that buffer or if
;; you have enabled it globally.
;;
;; When global and local blank-mode are on:
;;
;; * if local blank-mode is turned off, blank-mode is turned off for
;;   the current buffer only.
;;
;; * if global blank-mode is turned off, blank-mode continues on only
;;   in the buffers in which local blank-mode is on.
;;
;; To use blank-mode, insert in your ~/.emacs:
;;
;;    (require 'blank-mode)
;;
;; Or autoload at least one of the commands`blank-mode',
;; `blank-toggle-options', `global-blank-mode' or
;; `global-blank-toggle-options'.  For example:
;;
;;    (autoload 'blank-mode                  "blank-mode"
;;      "Toggle blank visualization."          t)
;;    (autoload 'blank-toggle-options        "blank-mode"
;;      "Toggle local `blank-mode' options."   t)
;;
;; blank-mode was inspired by:
;;
;;    whitespace.el            Rajesh Vaidheeswarran <rv@gnu.org>
;;      Warn about and clean bogus whitespaces in the file
;;      (inspired the idea to warn and clean some blanks)
;;
;;    show-whitespace-mode.el  Aurelien Tisne <aurelien.tisne@free.fr>
;;       Simple mode to highlight whitespaces
;;       (inspired the idea to use font-lock)
;;
;;    whitespace-mode.el       Lawrence Mitchell <wence@gmx.li>
;;       Major mode for editing Whitespace
;;       (inspired the idea to use display table)
;;
;;    visws.el                 Miles Bader <miles@gnu.org>
;;       Make whitespace visible
;;       (handle display table, his code was modified, but the main
;;       idea was kept)
;;
;;
;; Using blank-mode
;; ----------------
;;
;; There is no problem if you mix local and global minor mode usage.
;;
;; * LOCAL blank-mode:
;;    + To toggle blank-mode options locally, type:
;;
;;         M-x blank-toggle-options RET
;;
;;    + To activate blank-mode locally, type:
;;
;;         C-u 1 M-x blank-mode RET
;;
;;    + To deactivate blank-mode locally, type:
;;
;;         C-u 0 M-x blank-mode RET
;;
;;    + To toggle blank-mode locally, type:
;;
;;         M-x blank-mode RET
;;
;; * GLOBAL blank-mode:
;;    + To toggle blank-mode options globally, type:
;;
;;         M-x global-blank-toggle-options RET
;;
;;    + To activate blank-mode globally, type:
;;
;;         C-u 1 M-x global-blank-mode RET
;;
;;    + To deactivate blank-mode globally, type:
;;
;;         C-u 0 M-x global-blank-mode RET
;;
;;    + To toggle blank-mode globally, type:
;;
;;         M-x global-blank-mode RET
;;
;; There are also the following useful commands:
;;
;; `blank-cleanup'
;;    Cleanup some blank problems in all buffer or at region.
;;
;; `blank-cleanup-region'
;;    Cleanup some blank problems at region.
;;
;; The problems, which are cleaned up, are:
;;
;; 1. empty lines at beginning of buffer.
;; 2. empty lines at end of buffer.
;;    If `blank-chars' has `empty' as an element, remove all empty
;;    lines at beginning and/or end of buffer.
;;
;; 3. 8 or more SPACEs at beginning of line.
;;    If `blank-chars' has `indentation' as an element, replace 8 or
;;    more SPACEs at beginning of line by TABs.
;;
;; 4. SPACEs before TAB.
;;    If `blank-chars' has `space-before-tab' as an element, replace
;;    SPACEs by TABs.
;;
;; 5. SPACEs or TABs at end of line.
;;    If `blank-chars' has `trailing' as an element, remove all
;;    SPACEs or TABs at end of line."
;;
;; 6. 8 or more SPACEs after TAB.
;;    If `blank-chars' has `space-after-tab' as an element, replace
;;    SPACEs by TABs.
;;
;;
;; Hooks
;; -----
;;
;; blank-mode has the following hook variables:
;;
;; `blank-mode-hook'
;;    It is evaluated always when blank-mode is turned on locally.
;;
;; `global-blank-mode-hook'
;;    It is evaluated always when blank-mode is turned on globally.
;;
;; `blank-load-hook'
;;    It is evaluated after blank-mode package is loaded.
;;
;;
;; Options
;; -------
;;
;; Below it's shown a brief description of blank-mode options, please,
;; see the options declaration in the code for a long documentation.
;;
;; `blank-style'                Specify the visualization style.
;;
;; `blank-chars'                Specify which kind of blank is
;;                              visualized.
;;
;; `blank-space'                Face used to visualize SPACE.
;;
;; `blank-hspace'               Face used to visualize HARD SPACE.
;;
;; `blank-tab'                  Face used to visualize TAB.
;;
;; `blank-newline'              Face used to visualize NEWLINE char
;;                              mapping.
;;
;; `blank-trailing'             Face used to visualize trailing
;;                              blanks.
;;
;; `blank-line'                 Face used to visualize "long" lines.
;;
;; `blank-space-before-tab'     Face used to visualize SPACEs before
;;                              TAB.
;;
;; `blank-indentation'          Face used to visualize 8 or more
;;                              SPACEs at beginning of line.
;;
;; `blank-empty'                Face used to visualize empty lines at
;;                              beginning and/or end of buffer.
;;
;; `blank-space-after-tab'      Face used to visualize 8 or more
;;                              SPACEs after TAB.
;;
;; `blank-space-regexp'         Specify SPACE characters regexp.
;;
;; `blank-hspace-regexp'        Specify HARD SPACE characters regexp.
;;
;; `blank-tab-regexp'           Specify TAB characters regexp.
;;
;; `blank-trailing-regexp'      Specify trailing characters regexp.
;;
;; `blank-space-before-tab-regexp'      Specify SPACEs before TAB
;;                                      regexp.
;;
;; `blank-indentation-regexp'   Specify regexp for 8 or more SPACEs at
;;                              beginning of line.
;;
;; `blank-empty-at-bob-regexp'  Specify regexp for empty lines at
;;                              beginning of buffer.
;;
;; `blank-empty-at-eob-regexp'  Specify regexp for empty lines at end
;;                              of buffer.
;;
;; `blank-space-after-tab-regexp'       Specify regexp for 8 or more
;;                                      SPACEs after TAB.
;;
;; `blank-line-column'          Specify column beyond which the line
;;                              is highlighted.
;;
;; `blank-display-mappings'     Specify an alist of mappings for
;;                              displaying characters.
;;
;; `blank-global-modes'         Modes for which global `blank-mode' is
;;                              automagically turned on.
;;
;;
;; Acknowledgements
;; ----------------
;;
;; Thanks to nschum (EmacsWiki) for the idea about highlight "long"
;; lines tail.  See EightyColumnRule (EmacsWiki).
;;
;; Thanks to Juri Linkov <juri@jurta.org> for suggesting:
;;    * `define-minor-mode'.
;;    * `global-blank-*' name for global commands.
;;
;; Thanks to Robert J. Chassell <bob@gnu.org> for doc fix and testing.
;;
;; Thanks to Drew Adams <drew.adams@oracle.com> for toggle commands
;; suggestion.
;;
;; Thanks to Antti Kaihola <antti.kaihola@linux-aktivaattori.org> for
;; helping to fix `find-file-hooks' reference.
;;
;; Thanks to Andreas Roehler <andreas.roehler@easy-emacs.de> for
;; indicating defface byte-compilation warnings.
;;
;; Thanks to TimOCallaghan (EmacsWiki) for the idea about highlight
;; "long" lines.  See EightyColumnRule (EmacsWiki).
;;
;; Thanks to Yanghui Bian <yanghuibian@gmail.com> for indicating a new
;; newline character mapping.
;;
;; Thanks to Pete Forman <pete.forman@westgeo.com> for indicating
;; whitespace-mode on XEmacs.
;;
;; Thanks to Miles Bader <miles@gnu.org> for handling display table via
;; visws.el (his code was modified, but the main idea was kept).
;;
;; Thanks to:
;;    Rajesh Vaidheeswarran <rv@gnu.org>        whitespace.el
;;    Aurelien Tisne <aurelien.tisne@free.fr>   show-whitespace-mode.el
;;    Lawrence Mitchell <wence@gmx.li>          whitespace-mode.el
;;    Miles Bader <miles@gnu.org>               visws.el
;; And to all people who contributed with them.
;;
;;
;; ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

;;; code:

\f
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; User Variables:


;;; Interface to the command system


(defgroup blank nil
  "Visualize blanks (TAB, (HARD) SPACE and NEWLINE)."
  :link '(emacs-library-link :tag "Source Lisp File" "blank-mode.el")
  :version "22.2"
  :group 'wp
  :group 'data)


(defcustom blank-style '(mark color)
  "*Specify the visualization style.

It's a list which element value can be:

   mark         display mappings are visualized.

   color        faces are visualized.

Any other value is ignored.

If nil, don't visualize TABs, (HARD) SPACEs and NEWLINEs.

See also `blank-display-mappings' for documentation."
  :type '(repeat :tag "Style of Blank"
                 (choice :tag "Style of Blank"
                         (const :tag "Display Table" mark)
                         (const :tag "Faces" color)))
  :group 'blank)


(defcustom blank-chars
  '(tabs spaces trailing lines space-before-tab newline
         indentation empty space-after-tab)
  "*Specify which kind of blank is visualized.

It's a list which element value can be:

   trailing             trailing blanks are visualized.

   tabs                 TABs are visualized.

   spaces               SPACEs and HARD SPACEs are visualized.

   lines                lines whose have columns beyond
                        `blank-line-column' are highlighted.
                        Whole line is highlighted.
                        It has precedence over
                        `lines-tail' (see below).

   lines-tail           lines whose have columns beyond
                        `blank-line-column' are highlighted.
                        But only the part of line which goes
                        beyond `blank-line-column' column.
                        It has effect only if `lines' (see above)
                        is not present in `blank-chars'.

   space-before-tab     SPACEs before TAB are visualized.

   newline              NEWLINEs are visualized.

   indentation          8 or more SPACEs at beginning of line are
                        visualized.

   empty                empty lines at beginning and/or end of buffer
                        are visualized.

   space-after-tab      8 or more SPACEs after a TAB are visualized.

Any other value is ignored.

If nil, don't visualize TABs, (HARD) SPACEs and NEWLINEs.

Used when `blank-style' has `color' as an element.
If `blank-chars' has `newline' as an element, used when `blank-style'
has `mark' as an element."
  :type '(repeat :tag "Kind of Blank"
                 (choice :tag "Kind of Blank"
                         (const :tag "Trailing TABs, SPACEs and HARD SPACEs"
                                trailing)
                         (const :tag "SPACEs and HARD SPACEs" spaces)
                         (const :tag "TABs" tabs)
                         (const :tag "Lines" lines)
                         (const :tag "SPACEs before TAB"
                                space-before-tab)
                         (const :tag "NEWLINEs" newline)
                         (const :tag "Indentation SPACEs" indentation)
                         (const :tag "Empty Lines At BOB And/Or EOB"
                                empty)
                         (const :tag "SPACEs after TAB"
                                space-after-tab)))
  :group 'blank)


(defcustom blank-space 'blank-space
  "*Symbol face used to visualize SPACE.

Used when `blank-style' has `color' as an element."
  :type 'face
  :group 'blank)


(defface blank-space
  '((((class color) (background dark))
     (:background "grey20"      :foreground "aquamarine3"))
    (((class color) (background light))
     (:background "LightYellow" :foreground "aquamarine3"))
    (t (:inverse-video t)))
  "Face used to visualize SPACE."
  :group 'blank)


(defcustom blank-hspace 'blank-hspace
  "*Symbol face used to visualize HARD SPACE.

Used when `blank-style' has `color' as an element."
  :type 'face
  :group 'blank)


(defface blank-hspace                   ; 'nobreak-space
  '((((class color) (background dark))
     (:background "grey24"        :foreground "aquamarine3"))
    (((class color) (background light))
     (:background "LemonChiffon3" :foreground "aquamarine3"))
    (t (:inverse-video t)))
  "Face used to visualize HARD SPACE."
  :group 'blank)


(defcustom blank-tab 'blank-tab
  "*Symbol face used to visualize TAB.

Used when `blank-style' has `color' as an element."
  :type 'face
  :group 'blank)


(defface blank-tab
  '((((class color) (background dark))
     (:background "grey22" :foreground "aquamarine3"))
    (((class color) (background light))
     (:background "beige"  :foreground "aquamarine3"))
    (t (:inverse-video t)))
  "Face used to visualize TAB."
  :group 'blank)


(defcustom blank-newline 'blank-newline
  "*Symbol face used to visualize NEWLINE char mapping.

See `blank-display-mappings'.

Used when `blank-style' has `mark' and `color' as elements
and `blank-chars' has `newline' as an element."
  :type 'face
  :group 'blank)


(defface blank-newline
  '((((class color) (background dark))
     (:background "grey26" :foreground "aquamarine3" :bold t))
    (((class color) (background light))
     (:background "linen"  :foreground "aquamarine3" :bold t))
    (t (:bold t :underline t)))
  "Face used to visualize NEWLINE char mapping.

See `blank-display-mappings'."
  :group 'blank)


(defcustom blank-trailing 'blank-trailing
  "*Symbol face used to visualize traling blanks.

Used when `blank-style' has `color' as an element."
  :type 'face
  :group 'blank)


(defface blank-trailing                 ; 'trailing-whitespace
  '((((class mono)) (:inverse-video t :bold t :underline t))
    (t (:background "red1" :foreground "yellow" :bold t)))
  "Face used to visualize trailing blanks."
  :group 'blank)


(defcustom blank-line 'blank-line
  "*Symbol face used to visualize \"long\" lines.

See `blank-line-column'.

Used when `blank-style' has `color' as an element."
  :type 'face
  :group 'blank)


(defface blank-line
  '((((class mono)) (:inverse-video t :bold t :underline t))
    (t (:background "gray20" :foreground "violet")))
  "Face used to visualize \"long\" lines.

See `blank-line-column'."
  :group 'blank)


(defcustom blank-space-before-tab 'blank-space-before-tab
  "*Symbol face used to visualize SPACEs before TAB.

Used when `blank-style' has `color' as an element."
  :type 'face
  :group 'blank)


(defface blank-space-before-tab
  '((((class mono)) (:inverse-video t :bold t :underline t))
    (t (:background "DarkOrange" :foreground "firebrick")))
  "Face used to visualize SPACEs before TAB."
  :group 'blank)


(defcustom blank-indentation 'blank-indentation
  "*Symbol face used to visualize 8 or more SPACEs at beginning of line.

Used when `blank-style' has `color' as an element."
  :type 'face
  :group 'blank)


(defface blank-indentation
  '((((class mono)) (:inverse-video t :bold t :underline t))
    (t (:background "yellow" :foreground "firebrick")))
  "Face used to visualize 8 or more SPACEs at beginning of line."
  :group 'blank)


(defcustom blank-empty 'blank-empty
  "*Symbol face used to visualize empty lines at beginning and/or end of buffer.

Used when `blank-style' has `color' as an element."
  :type 'face
  :group 'blank)


(defface blank-empty
  '((((class mono)) (:inverse-video t :bold t :underline t))
    (t (:background "yellow" :foreground "firebrick")))
  "Face used to visualize empty lines at beginning and/or end of buffer."
  :group 'blank)


(defcustom blank-space-after-tab 'blank-space-after-tab
  "*Symbol face used to visualize 8 or more SPACEs after TAB.

Used when `blank-style' has `color' as an element."
  :type 'face
  :group 'blank)


(defface blank-space-after-tab
  '((((class mono)) (:inverse-video t :bold t :underline t))
    (t (:background "yellow" :foreground "firebrick")))
  "Face used to visualize 8 or more SPACEs after TAB."
  :group 'blank)


(defcustom blank-hspace-regexp
  "\\(\\(\xA0\\|\x8A0\\|\x920\\|\xE20\\|\xF20\\)+\\)"
  "*Specify HARD SPACE characters regexp.

If you're using `mule' package, it may exist other characters besides:

   \"\\xA0\"   \"\\x8A0\"   \"\\x920\"   \"\\xE20\"   \"\\xF20\"

that should be considered HARD SPACE.

Here are some examples:

   \"\\\\(^\\xA0+\\\\)\"                \
visualize only leading HARD SPACEs.
   \"\\\\(\\xA0+$\\\\)\"                \
visualize only trailing HARD SPACEs.
   \"\\\\(^\\xA0+\\\\|\\xA0+$\\\\)\"    \
visualize leading and/or trailing HARD SPACEs.
   \"\\t\\\\(\\xA0+\\\\)\\t\"           \
visualize only HARD SPACEs between TABs.

NOTE: Enclose always by \\\\( and \\\\) the elements to highlight.
      Use exactly one pair of enclosing \\\\( and \\\\).

Used when `blank-style' has `color' as an element, and
`blank-chars' has `spaces' as an element."
  :type '(regexp :tag "HARD SPACE Chars")
  :group 'blank)


(defcustom blank-space-regexp "\\( +\\)"
  "*Specify SPACE characters regexp.

If you're using `mule' package, it may exist other characters
besides \" \" that should be considered SPACE.

Here are some examples:

   \"\\\\(^ +\\\\)\"            visualize only leading SPACEs.
   \"\\\\( +$\\\\)\"            visualize only trailing SPACEs.
   \"\\\\(^ +\\\\| +$\\\\)\"    \
visualize leading and/or trailing SPACEs.
   \"\\t\\\\( +\\\\)\\t\"       visualize only SPACEs between TABs.

NOTE: Enclose always by \\\\( and \\\\) the elements to highlight.
      Use exactly one pair of enclosing \\\\( and \\\\).

Used when `blank-style' has `color' as an element, and
`blank-chars' has `spaces' as an element."
  :type '(regexp :tag "SPACE Chars")
  :group 'blank)


(defcustom blank-tab-regexp "\\(\t+\\)"
  "*Specify TAB characters regexp.

If you're using `mule' package, it may exist other characters
besides \"\\t\" that should be considered TAB.

Here are some examples:

   \"\\\\(^\\t+\\\\)\"          visualize only leading TABs.
   \"\\\\(\\t+$\\\\)\"          visualize only trailing TABs.
   \"\\\\(^\\t+\\\\|\\t+$\\\\)\"        \
visualize leading and/or trailing TABs.
   \" \\\\(\\t+\\\\) \" visualize only TABs between SPACEs.

NOTE: Enclose always by \\\\( and \\\\) the elements to highlight.
      Use exactly one pair of enclosing \\\\( and \\\\).

Used when `blank-style' has `color' as an element, and
`blank-chars' has `tabs' as an element."
  :type '(regexp :tag "TAB Chars")
  :group 'blank)


(defcustom blank-trailing-regexp
  "\t\\| \\|\xA0\\|\x8A0\\|\x920\\|\xE20\\|\xF20"
  "*Specify trailing characters regexp.

If you're using `mule' package, it may exist other characters besides:

   \" \"  \"\\t\"  \"\\xA0\"  \"\\x8A0\"  \"\\x920\"  \"\\xE20\"  \
\"\\xF20\"

that should be considered blank.

NOTE: DO NOT enclose by \\\\( and \\\\) the elements to highlight.
      `blank-mode' surrounds this regexp by \"\\\\(\\\\(\" and
      \"\\\\)+\\\\)$\".

Used when `blank-style' has `color' as an element, and
`blank-chars' has `trailing' as an element."
  :type '(regexp :tag "Trailing Chars")
  :group 'blank)


(defcustom blank-space-before-tab-regexp "\\( +\\)\t"
  "*Specify SPACEs before TAB regexp.

If you're using `mule' package, it may exist other characters besides:

   \" \"  \"\\t\"  \"\\xA0\"  \"\\x8A0\"  \"\\x920\"  \"\\xE20\"  \
\"\\xF20\"

that should be considered blank.

Used when `blank-style' has `color' as an element, and
`blank-chars' has `space-before-tab' as an element."
  :type '(regexp :tag "SPACEs Before TAB")
  :group 'blank)


(defcustom blank-indentation-regexp "^\t*\\(\\( \\{8\\}\\)+\\)[^\n\t]"
  "*Specify regexp for 8 or more SPACEs at beginning of line.

If you're using `mule' package, it may exist other characters besides:

   \" \"  \"\\t\"  \"\\xA0\"  \"\\x8A0\"  \"\\x920\"  \"\\xE20\"  \
\"\\xF20\"

that should be considered blank.

Used when `blank-style' has `color' as an element, and
`blank-chars' has `indentation' as an element."
  :type '(regexp :tag "Indentation SPACEs")
  :group 'blank)


(defcustom blank-empty-at-bob-regexp "\\`\\(\\([ \t]*\n\\)+\\)"
  "*Specify regexp for empty lines at beginning of buffer.

If you're using `mule' package, it may exist other characters besides:

   \" \"  \"\\t\"  \"\\xA0\"  \"\\x8A0\"  \"\\x920\"  \"\\xE20\"  \
\"\\xF20\"

that should be considered blank.

Used when `blank-style' has `color' as an element, and
`blank-chars' has `empty' as an element."
  :type '(regexp :tag "Empty Lines At Beginning Of Buffer")
  :group 'blank)


(defcustom blank-empty-at-eob-regexp "^\\([ \t\n]+\\)\\'"
  "*Specify regexp for empty lines at end of buffer.

If you're using `mule' package, it may exist other characters besides:

   \" \"  \"\\t\"  \"\\xA0\"  \"\\x8A0\"  \"\\x920\"  \"\\xE20\"  \
\"\\xF20\"

that should be considered blank.

Used when `blank-style' has `color' as an element, and
`blank-chars' has `empty' as an element."
  :type '(regexp :tag "Empty Lines At End Of Buffer")
  :group 'blank)


(defcustom blank-space-after-tab-regexp "\t\\(\\( \\{8\\}\\)+\\)"
  "*Specify regexp for 8 or more SPACEs after TAB.

If you're using `mule' package, it may exist other characters besides:

   \" \"  \"\\t\"  \"\\xA0\"  \"\\x8A0\"  \"\\x920\"  \"\\xE20\"  \
\"\\xF20\"

that should be considered blank.

Used when `blank-style' has `color' as an element, and
`blank-chars' has `space-after-tab' as an element."
  :type '(regexp :tag "SPACEs After TAB")
  :group 'blank)


(defcustom blank-line-column 80
  "*Specify column beyond which the line is highlighted.

Used when `blank-style' has `color' as an element, and
`blank-chars' has `lines' or `lines-tail' as an element."
  :type '(integer :tag "Line Length")
  :group 'blank)


;; Hacked from `visible-whitespace-mappings' in visws.el
(defcustom blank-display-mappings
  ;; Due to limitations of glyph representation, the char code can not
  ;; be above ?\x1FFFF.  Probably, this will be fixed after Emacs
  ;; unicode merging.
  '(
    (?\     [?\xB7]       [?.])         ; space - centered dot
    (?\xA0  [?\xA4]       [?_])         ; hard space - currency
    (?\x8A0 [?\x8A4]      [?_])         ; hard space - currency
    (?\x920 [?\x924]      [?_])         ; hard space - currency
    (?\xE20 [?\xE24]      [?_])         ; hard space - currency
    (?\xF20 [?\xF24]      [?_])         ; hard space - currency
    ;; NEWLINE is displayed using the face `blank-newline'
    (?\n    [?$ ?\n])                   ; end-of-line - dollar sign
    ;; (?\n    [?\u21B5 ?\n] [?$ ?\n])  ; end-of-line - downwards arrow
    ;; (?\n    [?\xB6 ?\n]   [?$ ?\n])  ; end-of-line - pilcrow
    ;; (?\n    [?\x8AF ?\n]  [?$ ?\n])  ; end-of-line - overscore
    ;; (?\n    [?\x8AC ?\n]  [?$ ?\n])  ; end-of-line - negation
    ;; (?\n    [?\x8B0 ?\n]  [?$ ?\n])  ; end-of-line - grade
    ;;
    ;; WARNING: the mapping below has a problem.
    ;; When a TAB occupies exactly one column, it will display the
    ;; character ?\xBB at that column followed by a TAB which goes to
    ;; the next TAB column.
    ;; If this is a problem for you, please, comment the line below.
    (?\t    [?\xBB ?\t]   [?\\ ?\t])    ; tab - left quote mark
    )
  "*Specify an alist of mappings for displaying characters.

Each element has the following form:

   (CHAR VECTOR...)

Where:

CHAR    is the character to be mapped.

VECTOR  is a vector of characters to be displayed in place of CHAR.
        The first display vector that can be displayed is used;
        if no display vector for a mapping can be displayed, then
        that character is displayed unmodified.

The NEWLINE character is displayed using the face given by
`blank-newline' variable.  The characters in the vector to be
displayed will not have this face applied if the character code
is above #x1FFFF.

Used when `blank-style' has `mark' as an element."
  :type '(repeat
          (list :tag "Character Mapping"
                (character :tag "Char")
                (repeat :inline t :tag "Vector List"
                        (vector :tag ""
                                (repeat :inline t
                                        :tag "Vector Characters"
                                        (character :tag "Char"))))))
  :group 'blank)


(defcustom blank-global-modes t
  "*Modes for which global `blank-mode' is automagically turned on.

Global `blank-mode' is controlled by the command `global-blank-mode'.

If nil, means no modes have `blank-mode' automatically turned on.
If t, all modes that support `blank-mode' have it automatically
turned on.
Else it should be a list of `major-mode' symbol names for
which `blank-mode' should be automatically turned on.  The sense
of the list is negated if it begins with `not'.  For example:

   (c-mode c++-mode)

means that `blank-mode' is turned on for buffers in C and C++
modes only."
  :type '(choice (const :tag "None" nil)
                 (const :tag "All" t)
                 (set :menu-tag "Mode Specific" :tag "Modes"
                      :value (not)
                      (const :tag "Except" not)
                      (repeat :inline t
                              (symbol :tag "Mode"))))
  :group 'blank)

\f
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; User commands - Local mode


;;;###autoload
(define-minor-mode blank-mode
  "Toggle blank minor mode visualization (\"bl\" on modeline).

If ARG is null, toggle blank visualization.
If ARG is a number greater than zero, turn on visualization;
otherwise, turn off visualization.
Only useful with a windowing system."
  :lighter    " bl"
  :init-value nil
  :global     nil
  :group      'blank
  (cond
   (noninteractive                      ; running a batch job
    (setq blank-mode nil))
   (blank-mode                          ; blank-mode on
    (blank-turn-on))
   (t                                   ; blank-mode off
    (blank-turn-off))))

\f
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; User commands - Global mode


(define-minor-mode global-blank-mode
  "Toggle blank global minor mode visualization (\"BL\" on modeline).

If ARG is null, toggle blank visualization.
If ARG is a number greater than zero, turn on visualization;
otherwise, turn off visualization.
Only useful with a windowing system."
  :lighter    " BL"
  :init-value nil
  :global     t
  :group      'blank
  (cond
   (noninteractive                      ; running a batch job
    (setq global-blank-mode nil))
   (global-blank-mode                   ; global-blank-mode on
    (save-excursion
      (if (boundp 'find-file-hook)
          (add-hook 'find-file-hook 'blank-turn-on-if-enabled t)
        (add-hook 'find-file-hooks 'blank-turn-on-if-enabled t))
      (dolist (buffer (buffer-list))    ; adjust all local mode
        (set-buffer buffer)
        (unless blank-mode
          (blank-turn-on-if-enabled)))))
   (t                                   ; global-blank-mode off
    (save-excursion
      (if (boundp 'find-file-hook)
          (remove-hook 'find-file-hook 'blank-turn-on-if-enabled)
        (remove-hook 'find-file-hooks 'blank-turn-on-if-enabled))
      (dolist (buffer (buffer-list))    ; adjust all local mode
        (set-buffer buffer)
        (unless blank-mode
          (blank-turn-off)))))))


(defun blank-turn-on-if-enabled ()
  (when (cond
         ((eq blank-global-modes t))
         ((listp blank-global-modes)
          (if (eq (car-safe blank-global-modes) 'not)
              (not (memq major-mode (cdr blank-global-modes)))
            (memq major-mode blank-global-modes)))
         (t nil))
    (let (inhibit-quit)
      ;; Don't turn on blank mode if...
      (or
       ;; ...we don't have a display (we're running a batch job)
       noninteractive
       ;; ...or if the buffer is invisible (name starts with a space)
       (eq (aref (buffer-name) 0) ?\ )
       ;; ...or if the buffer is temporary (name starts with *)
       (and (eq (aref (buffer-name) 0) ?*)
            ;; except the scratch buffer.
            (not (string= (buffer-name) "*scratch*")))
       ;; Otherwise, turn on blank mode.
       (blank-turn-on)))))

\f
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; User commands - Toggle


(defconst blank-chars-value-list
  '(tabs
    spaces
    trailing
    space-before-tab
    lines
    lines-tail
    newline
    indentation
    empty
    space-after-tab
    )
  "List of valid `blank-chars' values.")


(defconst blank-style-value-list
  '(color
    mark
    )
  "List of valid `blank-style' values.")


(defconst blank-toggle-option-alist
  '((?t . tabs)
    (?s . spaces)
    (?r . trailing)
    (?b . space-before-tab)
    (?l . lines)
    (?L . lines-tail)
    (?n . newline)
    (?i . indentation)
    (?e . empty)
    (?a . space-after-tab)
    (?c . color)
    (?m . mark)
    (?x . blank-chars)
    (?z . blank-style)
    )
  "Alist of toggle options.

Each element has the form:

   (CHAR . SYMBOL)

Where:

CHAR    is a char which the user will have to type.

SYMBOL  is a valid symbol associated with CHAR.
        See `blank-chars-value-list' and `blank-style-value-list'.")


(defvar blank-active-chars nil
  "Used to save locally `blank-chars' value.")
(make-variable-buffer-local 'blank-active-chars)

(defvar blank-active-style nil
  "Used to save locally `blank-style' value.")
(make-variable-buffer-local 'blank-active-style)


;;;###autoload
(defun blank-toggle-options (arg)
  "Toggle local `blank-mode' options.

If local blank-mode is off, toggle the option given by ARG and
turn on local blank-mode.

If local blank-mode is on, toggle the option given by ARG and
restart local blank-mode.

Interactively, it reads one of the following chars:

  CHAR  MEANING
   t    toggle TAB visualization
   s    toggle SPACE and HARD SPACE visualization
   r    toggle trailing blanks visualization
   b    toggle SPACEs before TAB visualization
   l    toggle \"long lines\" visualization
   L    toggle \"long lines\" tail visualization
   n    toggle NEWLINE visualization
   i    toggle indentation SPACEs visualization
   e    toggle empty line at bob and/or eob visualization
   a    toggle SPACEs after TAB visualization
   c    toggle color faces
   m    toggle visual mark
   x    restore `blank-chars' value
   z    restore `blank-style' value
   ?    display brief help

Non-interactively, ARG should be a symbol or a list of symbols.
The valid symbols are:

   tabs                 toggle TAB visualization
   spaces               toggle SPACE and HARD SPACE visualization
   trailing             toggle trailing blanks visualization
   space-before-tab     toggle SPACEs before TAB visualization
   lines                toggle \"long lines\" visualization
   lines-tail           toggle \"long lines\" tail visualization
   newline              toggle NEWLINE visualization
   indentation          toggle indentation SPACEs visualization
   empty                toggle empty line at bob and/or eob visualization
   space-after-tab      toggle SPACEs after TAB visualization
   color                toggle color faces
   mark                 toggle visual mark
   blank-chars          restore `blank-chars' value
   blank-style          restore `blank-style' value

Only useful with a windowing system."
  (interactive (blank-interactive-char t))
  (let ((blank-chars
         (blank-toggle-list t arg blank-active-chars blank-chars
                            'blank-chars blank-chars-value-list))
        (blank-style
         (blank-toggle-list t arg blank-active-style blank-style
                            'blank-style blank-style-value-list)))
    (blank-mode 0)
    (blank-mode 1)))


(defvar blank-toggle-chars nil
  "Used to toggle the global `blank-chars' value.")
(defvar blank-toggle-style nil
  "Used to toggle the global `blank-style' value.")


;;;###autoload
(defun global-blank-toggle-options (arg)
  "Toggle global `blank-mode' options.

If global blank-mode is off, toggle the option given by ARG and
turn on global blank-mode.

If global blank-mode is on, toggle the option given by ARG and
restart global blank-mode.

Interactively, it reads one of the following chars:

  CHAR  MEANING
   t    toggle TAB visualization
   s    toggle SPACE and HARD SPACE visualization
   r    toggle trailing blanks visualization
   b    toggle SPACEs before TAB visualization
   l    toggle \"long lines\" visualization
   L    toggle \"long lines\" tail visualization
   n    toggle NEWLINE visualization
   i    toggle indentation SPACEs visualization
   e    toggle empty line at bob and/or eob visualization
   a    toggle SPACEs after TAB visualization
   c    toggle color faces
   m    toggle visual mark
   x    restore `blank-chars' value
   z    restore `blank-style' value
   ?    display brief help

Non-interactively, ARG should be a symbol or a list of symbols.
The valid symbols are:

   tabs                 toggle TAB visualization
   spaces               toggle SPACE and HARD SPACE visualization
   trailing             toggle trailing blanks visualization
   space-before-tab     toggle SPACEs before TAB visualization
   lines                toggle \"long lines\" visualization
   lines-tail           toggle \"long lines\" tail visualization
   newline              toggle NEWLINE visualization
   indentation          toggle indentation SPACEs visualization
   empty                toggle empty line at bob and/or eob visualization
   space-after-tab      toggle SPACEs after TAB visualization
   color                toggle color faces
   mark                 toggle visual mark
   blank-chars          restore `blank-chars' value
   blank-style          restore `blank-style' value

Only useful with a windowing system."
  (interactive (blank-interactive-char nil))
  (let ((blank-chars
         (blank-toggle-list nil arg blank-toggle-chars blank-chars
                            'blank-chars blank-chars-value-list))
        (blank-style
         (blank-toggle-list nil arg blank-toggle-style blank-style
                            'blank-style blank-style-value-list)))
    (setq blank-toggle-chars blank-chars
          blank-toggle-style blank-style)
    (global-blank-mode 0)
    (global-blank-mode 1)))

\f
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; User commands - Cleanup


;;;###autoload
(defun blank-cleanup ()
  "Cleanup some blank problems in all buffer or at region.

It usually applies to the whole buffer, but in transient mark
mode when the mark is active, it applies to the region.  It also
applies to the region when it is not in transiente mark mode, the
mark is active and it was pressed `C-u' just before calling
`blank-cleanup' interactively.

See also `blank-cleanup-region'.

The problems, which are cleaned up, are:

1. empty lines at beginning of buffer.
2. empty lines at end of buffer.
   If `blank-chars' has `empty' as an element, remove all empty
   lines at beginning and/or end of buffer.

3. 8 or more SPACEs at beginning of line.
   If `blank-chars' has `indentation' as an element, replace 8 or
   more SPACEs at beginning of line by TABs.

4. SPACEs before TAB.
   If `blank-chars' has `space-before-tab' as an element, replace
   SPACEs by TABs.

5. SPACEs or TABs at end of line.
   If `blank-chars' has `trailing' as an element, remove all
   SPACEs or TABs at end of line.

6. 8 or more SPACEs after TAB.
   If `blank-chars' has `space-after-tab' as an element, replace
   SPACEs by TABs."
  (interactive "@*")
  (if (and (or transient-mark-mode
               current-prefix-arg)
           mark-active)
      ;; region active
      ;; problems 1 and 2 are not handled in region
      ;; problem 3: 8 or more SPACEs at bol
      ;; problem 4: SPACEs before TAB
      ;; problem 5: SPACEs or TABs at eol
      ;; problem 6: 8 or more SPACEs after TAB
      (blank-cleanup-region (region-beginning) (region-end))
    ;; whole buffer
    (save-excursion
      (save-match-data
        ;; problem 1: empty lines at bob
        ;; problem 2: empty lines at eob
        ;; action: remove all empty lines at bob and/or eob
        (when (memq 'empty blank-chars)
          (let (overwrite-mode)         ; enforce no overwrite
            (goto-char (point-min))
            (when (re-search-forward blank-empty-at-bob-regexp nil t)
              (delete-region (match-beginning 1) (match-end 1)))
            (when (re-search-forward blank-empty-at-eob-regexp nil t)
              (delete-region (match-beginning 1) (match-end 1)))))))
    ;; problem 3: 8 or more SPACEs at bol
    ;; problem 4: SPACEs before TAB
    ;; problem 5: SPACEs or TABs at eol
    ;; problem 6: 8 or more SPACEs after TAB
    (blank-cleanup-region (point-min) (point-max))))


;;;###autoload
(defun blank-cleanup-region (start end)
  "Cleanup some blank problems at region.

The problems, which are cleaned up, are:

1. 8 or more SPACEs at beginning of line.
   If `blank-chars' has `indentation' as an element, replace 8 or
   more SPACEs at beginning of line by TABs.

2. SPACEs before TAB.
   If `blank-chars' has `space-before-tab' as an element, replace
   SPACEs by TABs.

3. SPACEs or TABs at end of line.
   If `blank-chars' has `trailing' as an element, remove all
   SPACEs or TABs at end of line.

4. 8 or more SPACEs after TAB.
   If `blank-chars' has `space-after-tab' as an element, replace
   SPACEs by TABs."
  (interactive "@*r")
  (let ((rstart           (min start end))
        (rend             (copy-marker (max start end)))
        (tab-width        8)            ; assure TAB width
        (indent-tabs-mode t)            ; always insert TABs
        overwrite-mode                  ; enforce no overwrite
        tmp)
    (save-excursion
      (save-match-data
        ;; problem 1: 8 or more SPACEs at bol
        ;; action: replace 8 or more SPACEs at bol by TABs
        (when (memq 'indentation blank-chars)
          (goto-char rstart)
          (while (re-search-forward blank-indentation-regexp rend t)
            (setq tmp (current-indentation))
            (delete-horizontal-space)
            (unless (eolp)
              (indent-to tmp))))
        ;; problem 3: SPACEs or TABs at eol
        ;; action: remove all SPACEs or TABs at eol
        (when (memq 'trailing blank-chars)
          (let ((regexp (concat "\\(\\(" blank-trailing-regexp
                                "\\)+\\)$")))
            (goto-char rstart)
            (while (re-search-forward regexp rend t)
              (delete-region (match-beginning 1) (match-end 1)))))
        ;; problem 4: 8 or more SPACEs after TAB
        ;; action: replace 8 or more SPACEs by TABs
        (when (memq 'space-after-tab blank-chars)
          (blank-replace-spaces-by-tabs
           rstart rend blank-space-after-tab-regexp))
        ;; problem 2: SPACEs before TAB
        ;; action: replace SPACEs before TAB by TABs
        (when (memq 'space-before-tab blank-chars)
          (blank-replace-spaces-by-tabs
           rstart rend blank-space-before-tab-regexp))))
    (set-marker rend nil)))             ; point marker to nowhere


(defun blank-replace-spaces-by-tabs (rstart rend regexp)
  "Replace all SPACEs by TABs matched by REGEXP between RSTART and REND."
  (goto-char rstart)
  (while (re-search-forward regexp rend t)
    (goto-char (match-beginning 1))
    (let* ((scol (current-column))
           (ecol (save-excursion
                   (goto-char (match-end 1))
                   (current-column))))
      (delete-region (match-beginning 1) (match-end 1))
      (insert-char ?\t
                   (/ (- (- ecol (% ecol 8))        ; prev end col
                         (- scol (% scol 8)))       ; prev start col
                      8)))))

\f
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; Internal functions


(defvar blank-font-lock-mode nil
  "Used to remember whether a buffer had font lock mode on or not.")
(make-variable-buffer-local 'blank-font-lock-mode)

(defvar blank-font-lock nil
  "Used to remember whether a buffer initially had font lock on or not.")
(make-variable-buffer-local 'blank-font-lock)

(defvar blank-font-lock-keywords nil
  "Used to save locally `font-lock-keywords' value.")
(make-variable-buffer-local 'blank-font-lock-keywords)


(defconst blank-help-text
  "\
      blank-mode toggle options:

 []  t - toggle TAB visualization
 []  s - toggle SPACE and HARD SPACE visualization
 []  r - toggle trailing blanks visualization
 []  b - toggle SPACEs before TAB visualization
 []  l - toggle \"long lines\" visualization
 []  L - toggle \"long lines\" tail visualization
 []  n - toggle NEWLINE visualization
 []  i - toggle indentation SPACEs visualization
 []  e - toggle empty line at bob and/or eob visualization
 []  a - toggle SPACEs after TAB visualization

 []  c - toggle color faces
 []  m - toggle visual mark

      x - restore `blank-chars' value
      z - restore `blank-style' value

      ? - display this text\n\n"
  "Text for blank toggle options.")


(defconst blank-help-buffer-name "*Blank Toggle Options*"
  "The buffer name for blank toggle options.")


(defun blank-insert-option-mark (the-list the-value)
  "Insert the option mark ('X' or ' ') in toggle options buffer."
  (forward-line 1)
  (dolist (sym  the-list)
    (forward-line 1)
    (forward-char 2)
    (insert (if (memq sym the-value) "X" " "))))


(defun blank-help-on (chars style)
  "Display the blank toggle options."
  (unless (get-buffer blank-help-buffer-name)
    (delete-other-windows)
    (let ((buffer (get-buffer-create blank-help-buffer-name)))
      (save-excursion
        (set-buffer buffer)
        (erase-buffer)
        (insert blank-help-text)
        (goto-char (point-min))
        (blank-insert-option-mark blank-chars-value-list chars)
        (blank-insert-option-mark blank-style-value-list style)
        (goto-char (point-min))
        (set-buffer-modified-p nil)
        (let ((size (- (window-height)
                       (max window-min-height
                            (1+ (count-lines (point-min) (point-max)))))))
          (when (<= size 0)
            (kill-buffer buffer)
            (error "Frame height is too small; \
can't split window to display blank toggle options"))
          (set-window-buffer (split-window nil size) buffer))))))


(defun blank-help-off ()
  "Remove the buffer and window of the blank toggle options."
  (let ((buffer (get-buffer blank-help-buffer-name)))
    (when buffer
      (delete-windows-on buffer)
      (kill-buffer buffer))))


(defun blank-interactive-char (local-p)
  "Interactive function to read a char and return a symbol.

If LOCAL-P is non-nil, it uses a local context; otherwise, it
uses a global context.

It reads one of the following chars:

  CHAR  MEANING
   t    toggle TAB visualization
   s    toggle SPACE and HARD SPACE visualization
   r    toggle trailing blanks visualization
   b    toggle SPACEs before TAB visualization
   l    toggle \"long lines\" visualization
   L    toggle \"long lines\" tail visualization
   n    toggle NEWLINE visualization
   i    toggle indentation SPACEs visualization
   e    toggle empty line at bob and/or eob visualization
   a    toggle SPACEs after TAB visualization
   c    toggle color faces
   m    toggle visual mark
   x    restore `blank-chars' value
   z    restore `blank-style' value
   ?    display brief help

See also `blank-toggle-option-alist'."
  (let* ((is-off (not (if local-p blank-mode global-blank-mode)))
         (chars  (cond (is-off  blank-chars) ; use default value
                       (local-p blank-active-chars)
                       (t       blank-toggle-chars)))
         (style  (cond (is-off  blank-style) ; use default value
                       (local-p blank-active-style)
                       (t       blank-toggle-style)))
         (prompt
          (format "Blank Toggle %s (type ? for further options)-"
                  (if local-p "Local" "Global")))
         ch sym)
    ;; read a valid option and get the corresponding symbol
    (save-window-excursion
      (condition-case data
          (progn
            (while
                ;; while condition
                (progn
                  (setq ch (read-char prompt))
                  (not
                   (setq sym
                         (cdr (assq ch blank-toggle-option-alist)))))
              ;; while body
              (if (eq ch ?\?)
                  (blank-help-on chars style)
                (ding)))
            (blank-help-off)
            (message " "))              ; clean echo area
        ;; handler
        ((quit error)
         (blank-help-off)
         (error (error-message-string data)))))
    (list sym)))                        ; return the apropriate symbol


(defun blank-toggle-list (local-p arg the-list default-list
                                  sym-restore sym-list)
  "Toggle options in THE-LIST based on list ARG.

If LOCAL-P is non-nil, it uses a local context; otherwise, it
uses a global context.

ARG is a list of options to be toggled.

THE-LIST is a list of options.  This list will be toggled and the
resultant list will be returned.

DEFAULT-LIST is the default list of options.  It is used to
restore the options in THE-LIST.

SYM-RESTORE is the symbol which indicates to restore the options
in THE-LIST.

SYM-LIST is a list of valid options, used to check if the ARG's
options are valid."
  (unless (if local-p blank-mode global-blank-mode)
    (setq the-list default-list))
  (setq the-list (copy-sequence the-list)) ; keep original list
  (dolist (sym (if (listp arg) arg (list arg)))
    (cond
     ;; restore default values
     ((eq sym sym-restore)
      (setq the-list default-list))
     ;; toggle valid values
     ((memq sym sym-list)
      (setq the-list (if (memq sym the-list)
                         (delq sym the-list)
                       (cons sym the-list))))))
  the-list)


(defun blank-turn-on ()
  "Turn on blank visualization."
  (setq blank-active-style (if (listp blank-style)
                               blank-style
                             (list blank-style)))
  (setq blank-active-chars (if (listp blank-chars)
                               blank-chars
                             (list blank-chars)))
  (when (memq 'color blank-active-style)
    (blank-color-on))
  (when (memq 'mark  blank-active-style)
    (blank-display-char-on)))


(defun blank-turn-off ()
  "Turn off blank visualization."
  (when (memq 'color blank-active-style)
    (blank-color-off))
  (when (memq 'mark  blank-active-style)
    (blank-display-char-off)))


(defun blank-color-on ()
  "Turn on color visualization."
  (when blank-active-chars
    (unless blank-font-lock
      (setq blank-font-lock t
            blank-font-lock-keywords
            (copy-sequence font-lock-keywords)))
    ;; turn off font lock
    (setq blank-font-lock-mode font-lock-mode)
    (font-lock-mode 0)
    ;; add blank-mode color into font lock
    (when (memq 'spaces blank-active-chars)
      (font-lock-add-keywords
       nil
       (list
        ;; Show SPACEs
        (list blank-space-regexp  1 blank-space  t)
        ;; Show HARD SPACEs
        (list blank-hspace-regexp 1 blank-hspace t))
       t))
    (when (memq 'tabs blank-active-chars)
      (font-lock-add-keywords
       nil
       (list
        ;; Show TABs
        (list blank-tab-regexp 1 blank-tab t))
       t))
    (when (memq 'trailing blank-active-chars)
      (font-lock-add-keywords
       nil
       (list
        ;; Show trailing blanks
        (list (concat "\\(\\(" blank-trailing-regexp "\\)+\\)$")
              1 blank-trailing t))
       t))
    (when (or (memq 'lines      blank-active-chars)
              (memq 'lines-tail blank-active-chars))
      (font-lock-add-keywords
       nil
       (list
        ;; Show "long" lines
        (list
         (format
          "^\\([^\t\n]\\{%s\\}\\|[^\t\n]\\{0,%s\\}\t\\)\\{%d\\}%s\\(.+\\)$"
          tab-width (1- tab-width)
          (/ blank-line-column tab-width)
          (let ((rem (% blank-line-column tab-width)))
            (if (zerop rem)
                ""
              (format ".\\{%d\\}" rem))))
         (if (memq 'lines blank-active-chars)
             0                          ; whole line
           2)                           ; line tail
         blank-line t))
       t))
    (when (memq 'space-before-tab blank-active-chars)
      (font-lock-add-keywords
       nil
       (list
        ;; Show SPACEs before TAB
        (list blank-space-before-tab-regexp
              1 blank-space-before-tab t))
       t))
    (when (memq 'indentation blank-active-chars)
      (font-lock-add-keywords
       nil
       (list
        ;; Show indentation SPACEs
        (list blank-indentation-regexp
              1 blank-indentation t))
       t))
    (when (memq 'empty blank-active-chars)
      (font-lock-add-keywords
       nil
       (list
        ;; Show empty lines at beginning of buffer
        (list blank-empty-at-bob-regexp
              1 blank-empty t))
       t)
      (font-lock-add-keywords
       nil
       (list
        ;; Show empty lines at end of buffer
        (list blank-empty-at-eob-regexp
              1 blank-empty t))
       t))
    (when (memq 'space-after-tab blank-active-chars)
      (font-lock-add-keywords
       nil
       (list
        ;; Show SPACEs after TAB
        (list blank-space-after-tab-regexp
              1 blank-space-after-tab t))
       t))
    ;; now turn on font lock and highlight blanks
    (font-lock-mode 1)))


(defun blank-color-off ()
  "Turn off color visualization."
  (when blank-active-chars
    ;; turn off font lock
    (font-lock-mode 0)
    (when blank-font-lock
      (setq blank-font-lock nil
            font-lock-keywords blank-font-lock-keywords))
    ;; restore original font lock state
    (font-lock-mode blank-font-lock-mode)))

\f
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;; Hacked from visws.el (Miles Bader <miles@gnu.org>)


(defvar blank-display-table nil
  "Used to save a local display table.")
(make-variable-buffer-local 'blank-display-table)

(defvar blank-display-table-was-local nil
  "Used to remember whether a buffer initially had a local display table or not.")
(make-variable-buffer-local 'blank-display-table-was-local)


(defsubst blank-char-valid-p (char)
  ;; This check should be improved!!!
  (or (< char 256)
      (char-valid-p char)))


(defun blank-legal-display-vector-p (vec)
  "Return true if every character in vector VEC can be displayed."
  (let ((i (length vec)))
    (when (> i 0)
      (while (and (>= (setq i (1- i)) 0)
                  (blank-char-valid-p (aref vec i))))
      (< i 0))))


(defun blank-display-char-on ()
  "Turn on character display mapping."
  (when blank-display-mappings
    (let (vecs vec)
      ;; Remember whether a buffer has a local display table.
      (unless blank-display-table-was-local
        (setq blank-display-table-was-local t
              blank-display-table
              (copy-sequence buffer-display-table)))
      (unless buffer-display-table
        (setq buffer-display-table (make-display-table)))
      (dolist (entry blank-display-mappings)
        (setq vecs (cdr entry))
        ;; Get a displayable mapping.
        (while (and vecs
                    (not (blank-legal-display-vector-p (car vecs))))
          (setq vecs (cdr vecs)))
        ;; Display a valid mapping.
        (when vecs
          (setq vec (copy-sequence (car vecs)))
          (cond
           ;; Any char except newline
           ((not (eq (car entry) ?\n))
            (aset buffer-display-table (car entry) vec))
           ;; Newline char - display it
           ((memq 'newline blank-active-chars)
            ;; Only insert face bits on NEWLINE char mapping to avoid
            ;; obstruction of other faces like TABs and (HARD) SPACEs
            ;; faces, font-lock faces, etc.
            (when (memq 'color blank-active-style)
              (dotimes (i (length vec))
                ;; Due to limitations of glyph representation, the char
                ;; code can not be above ?\x1FFFF.  Probably, this will
                ;; be fixed after Emacs unicode merging.
                (or (eq (aref vec i) ?\n)
                    (> (aref vec i) #x1FFFF)
                    (aset vec i (make-glyph-code (aref vec i)
                                                 blank-newline)))))
            ;; Display mapping
            (aset buffer-display-table (car entry) vec))
           ;; Newline char - don't display it
           (t
            ;; Do nothing
            )))))))


(defun blank-display-char-off ()
  "Turn off character display mapping."
  (and blank-display-mappings
       blank-display-table-was-local
       (setq blank-display-table-was-local nil
             buffer-display-table          blank-display-table)))

\f
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


(provide 'blank-mode)


(run-hooks 'blank-load-hook)


;; arch-tag: 1b1e2500-dbd4-4a26-8f7a-5a5edfd3c97e
;;; blank-mode.el ends here